1. Field of the Invention
The invention relates to a system for providing remote control of ground treatment or working devices, such as self-powered ground-compaction devices. The system includes a hand-held device that wirelessly communicates with the ground working device via two different frequency communication protocols such that the system enhances the control associated with operation of the ground treatment via an operator that is proximate but remote therefrom.
2. Description of the Related Art
One way of remotely controlling ground working devices is to provide a cable connection between the working device and a transmitter associated with a remote control device. Several wires are commonly accommodated in the cable connection and tether the remote control device to the working device such that the operator can control operation of the working device from locations slightly remove by still very proximate to the working device. The cable connection serves to transmit control commands from the transmitter of the remote control device to the working device. The transmitter is commonly supplied with power from the working device via the cable connection. Such a configuration provides continuous communication between control and working devices but commonly requires close proximity between the operator and the working device wherein the range of this proximity is controlled by the length of the cable connection that extends therebetween.
Commonly, the length of the cable connection is configured to prevent certain interaction between the operator, the working environment, and the working device. For instance, the cable connection is commonly configured to define a designated operating area associated with the position or location of the operator relative to the working device. The length of the cable connection is commonly dimensioned such that the operator is unable to enter the travel path associated with movement of the working device. Such systems also commonly include one or more safety devices, such as protective bars, pressure bars, limit switches, or the like which interfere with operation of the working device or even reverse the direction of travel of the working device if the operator comes into contact with a respective safety device. Such safety devices are however susceptible to damage and/or inoperability when the working device is operated in close proximity to other devices and/or structures associated with the working environment. For instance, respective brackets associated with such safety devices can be bent or torn from the working device effectively rendering the safety device inoperable or ill-suited to suspend or otherwise interfere with operation of the working device when desired, anticipated, or expected.
A further disadvantage of such remote cable control is attributable to the restrictive length of the cable which forces the operator to constantly follow the working device to maintain the necessary proximity thereto. Such a configuration leaves the operator continuously exposed to noise, exhaust gases, vibrations, etc. commonly associated with operation of working device, other devices or machines that may be operating in the vicinity, and other dirt and uneven terrain common to such environments.
To obviate one or more of the aforementioned disadvantages, others have implemented ground treatment machines having remote control devices which operate via an infrared communication protocol. Such wireless communication interfaces provide a modulated infrared light that is communicated between a transmitting unit and a receiving unit that are associated with one of the control device and the working device. Such infrared remote control systems commonly require a constant visual or line-of-sight communication interface between the control device and the working device. If the operator fails to maintain the line-of-sight proximity, such as can occur should the operator stumble or fall or other structures or devices interfere with the line-of-sight communication, the infrared signal is interrupted resulting in suspension of operation of the working device.
DE 42 21 793 C1 discloses one such infrared remote control for a ground-compaction device and implements a control device that is carried by the operator. The control device transmits not only the infrared communication providing for the functional control of the working device but also a short-range infrared radiation communication at a substantially lower intensity than the radiation associated with the infrared control radiation communication. This short-range radiation can only be received with sufficient intensity in the immediate area surrounding the transmitter.
Upon reception of the short-range radiation, indicating a close proximity of the working device to the control device—and thereby the operator, the receiving unit associated with the working device suppresses the generation of electrical signals caused by receipt of the control radiation so as to suspend operation of the working device if such proximity occurs. That is, the infrared remote control system of DE 42 21 793 C1 allows operation of the working device provided the working device is located within a receiving range of the control radiation but outside the range of the short-range radiation communication. If the distance between the operator and the working device is less than a predetermined distance, i.e. if the short-range radiation is received by the receiving unit associated with the working device, operation of the working device is suspended. The short-range radiation signal provides a wireless proximity safety device whose purpose is similar to the physical safety devices as described above.
One disadvantage of such infrared control systems is the substantial amount of power that is required to generate and maintain the signals associated with the modulated and short-range infrared communications. Operator support of that part of the power system associate with the remote control device, and the power source necessary thereto, can accelerate operator fatigue and limits the duration of operation of the system between recharges or replacements of the power source. Further, incidence of insufficient battery power associated with either operation of the transmitter or receiver of the infrared wireless communication can lead to adverse interruptions in operation of the working device and/or control system.
DE 41 39 041 A1 describes a remote control device which can be operated both as a wired and wireless system. A detector establishes whether a signal transmission cable is connected to the device, and outputs a corresponding signal to switch the device between the hardwired and wireless operating systems. During the wire-connection operation, the control signals are transmitted via the cable which connects a transmitter to a receiver. In addition, the cable serves to supply power to the transmitter. Such a system is susceptible to the one or more of the drawbacks discussed above with respect to the discrete wired or wireless control of the working device.
U.S. Pat. Nos. 5,450,068 and 6,997,648, the disclosures of both of which are attributable to the commercial efforts of the present applicant and which are incorporated herein, disclose remote control systems for remotely controlled operation of ground treatment devices that overcome one or more of the drawbacks discussed above. U.S. Pat. No. 6,997,648 discloses a remote control device that includes a transmitter unit which can be actuated by a user and which is used to transmit control signals in the form of electromagnetic radiation. A receiver unit is arranged on the working device and outputs the received control signals in the form of electronic control commands to the control unit of a working device.
During operation of the working device, the transmitter unit can be connected to an external power source, which is arranged on the working device, via a cable for the supply of power thereto. Such a configuration allows reliable operation of the control system for lengthy operating periods without compromise to efficient transmission of control signals at high transmission power. However, it is believed room exists for improving the efficient and reliable wireless communication between a remote operator control and a working device in a manner that does not detrimentally affect operator or other personnel safety and which better accommodates interferences associated with the operating environment.